Gene therapy has significant promise for the treatment of neurodegeneration. However, current gene delivery technology must be engineered for improved delivery efficiency, targeting to affected cell types, and the ability to transduce large and often surgically inaccessible regions of tissue. The recent findings that AAV vectors undergo retrograde transport along axonal projections also raises the intriguing possibility for efficient targeting and delivery of therapeutic payloads to cells that are delicate and otherwise difficult to surgically access such as motor neurons residing in the spinal cord. However, we have found that the efficiency of AAV retrograde transport can be limiting in a mouse model. We therefore propose to employ a directed molecular evolution approach to develop novel AAV capsid variants with enhanced retrograde transport in vivo. We anticipate this work may significantly improve the therapeutic efficacy and cost effectiveness of retrogradely delivered biologics to target difficult to access areas of the nervous system. Improvements in the retrograde transport ability of AAV would therefore allow more efficient delivery to spinal cord motor neurons for numerous diseases including Amyotrophic Lateral Sclerosis (ALS) and spinal cord injury. Our Specific Aims are: 1. To determine whether directed evolution can yield AAV variants with enhanced retrograde transport properties in vivo. 2. To characterize the enhanced retrograde transport variants for transduction efficiency and analyze sequence-function relationships for in vivo gene delivery of reporter genes. 3. To determine whether retrograde transport variants harboring the neuroprotective gene IGF-1 can enhance therapeutic efficacy in a mouse model of ALS. We believe the development of our library of AAV mutants will provide for novel reagents to be provided to the research community.